Classroom Extra concludes Women’s History Month with a look at a few items we can’t live without – courtesy of some very inventive ladies.

A new wrinkle on the old nylon

Julie Newmar is a Hollywood legend. One of her most famous roles was “Catwoman” in the Batman TV series in the 1960s. But she’s known off-screen for an invention that your mother probably uses everyday – pantyhose.

Nylon stockings were first introduced to the public at the 1939 World’s Fair. They were said to be as “strong as steel and as sheer as a spider web.” While Allan Grant Sr. actually invented the combination of nylon stockings and underpants, Newmar holds the patent for the ultra sheer, super snug variety. What other type would a super chic villain like Catwoman wear?

A head for science

Actress Hedi Lamarr was more than just another pretty face. She and musician George Antheil made their contribution to the World War II effort by developing an electronic communications system that effectively manipulated radio frequencies into code.

While this might sound like mumbo jumbo, their invention helped torpedoes hit their targets by preventing their signals from getting jammed by the enemy.

The system is based on frequency hopping. Here’s how it works:

Instead of transmitting a signal on one frequency, the spectrum system switches quickly from one frequency to the next, Making it almost impossible to pick it up.

The cordless phone in your home uses a digital version of the spectrum system. Unfortunately for Lamarr and Antheil, the patent expired before they made any real money, but their invention was recognized with an Electronic Frontier Foundation’s Pioneer Award.

Painting makes perfect

Liquid Paper, that little bottle of “paint” that hides our mistakes, was invented by a smart secretary with less than perfect typing skills. In 1956, Bette Nesmith Graham was mixing up batches of her miracle cover-up in her kitchen.

Her bad typing cost her the secretary’s job, but opened the door for her to produce and market her invention. She became independently-wealthy. Her son Michael became famous with the ’60s band The Monkees.

The self-cleaning house

The ultimate do-it-all invention has to be Frances Gabe’s self-cleaning house. Gabe learned about design from her architect father and later married an engineer. She developed the radical but practical idea because she just plain hated housework.

The house features a multi-functional ceiling unit that heats, cools, cleans and dries everything. The walls and floors are coated with resin. There are no dust-collecting rugs. The bookshelves dust themselves. The kitchen cabinets double as dishwashers, and the closets wash, dry and store clothes.

Maybe, one day, we’ll all have self-cleaning units and you’ll never have to clean your room again.

Now see this

Katherine Blodgett was a pioneering woman. She was the first female to earn a Ph.D. from Cambridge University and the first female scientist hired by General Electric.

It was at GE that she discovered a way to apply monomolecular coatings in layers to glass. The process resulted in the 100 percent nonreflective glass used in eyeglasses, cameras and telescopes.

No more dishpan hands

At the 1893 World’s Fair, Josephine Chochran unveiled a wooden hand-operated device that splashed water on dirty dishes.

Hotels and restaurants loved it, but her dishwasher didn’t make a big splash with the general public until the 1950s.

Cochran’s company went on to become a premier manufacturer of devices that today, make life in the kitchen easier – Kitchen Aid.